Area Forecast Discussion
Issued by NWS Salt Lake City, UT

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000
FXUS65 KSLC 271124
AFDSLC

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SALT LAKE CITY UT
424 AM MST FRI FEB 27 2015

.SYNOPSIS..A DEVELOPING WINTER STORM SYSTEM WILL AFFECT MUCH OF
THE SOUTHERN AND CENTRAL GREAT BASIN THIS WEEKEND. A SECOND STORM
WILL FOLLOW THE WEEKEND STORM EARLY NEXT WEEK.

&&

.SHORT TERM (THROUGH 00Z TUESDAY)...THE UPPER TROUGH POSITIONED
OFF THE WASHINGTON COAST EARLY THIS MORNING STILL ON TRACK TO
DEVELOP INTO A SIGNIFICANT WINTER STORM FOR SOUTHERN/CENTRAL UTAH
THIS WEEKEND. THIS TROUGH WILL EVENTUALLY FORM A WEAK CIRCULATION
AS IT SETTLES INTO CENTRAL CALIFORNIA AND THE WESTERN GREAT BASIN
LATE TONIGHT/SATURDAY. THIS FEATURE WILL TURN EAST-SOUTHEAST AND
BECOME AN OPEN WAVE AGAIN AS IT TRACKS INTO THE SOUTHERN GREAT
BASIN/DESERT SOUTHWEST LATE IN THE WEEKEND.

FOR TODAY THE MEAN FLOW ALOFT WILL BACK AROUND TO A MORE WESTERLY
DIRECTION WITH A COOL/MOIST AIR MASS REMAINING IN PLACE ACROSS THE
GREAT BASIN. WILL LIKELY SEE A WEAK DISTURBANCE OR TWO EJECT OUT
AHEAD OF THE DEVELOPING UPPER LOW ALONG THE WEST COAST. WEAK
DYNAMIC LIFT WORKING ON THE AMBIENT AIR MASS OVER UTAH COULD
GENERATE SOME LIGHT PRECIP TODAY. WILL KEEP LOW-END POPS IN PLACE
ACROSS MUCH OF THE STATE...WITH MINIMAL PRECIP EXPECTED.

ORGANIZED PRECIP THIS EVENING WITH THE NOW DEVELOPED UPPER LOW
WILL CONCENTRATE ACROSS SOUTHERN UTAH. AN OLD BUT LOOSELY DEFINED
BAROCLINIC ZONE OVER SOUTHERN UTAH/NORTHERN ARIZONA WILL BE THE
FOCUS FOR HEAVIER PRECIP. SHORTWAVE ENERGY EJECTING OUT AHEAD OF
THE UPPER LOW ALONG THIS BOUNDARY COMBINED WITH GOOD UPPER
DIVERGENCE IN THE LEFT EXIT REGION OF THE JET WILL GENERATE DEEP
AND FAIRLY STRONG UPWARD MOTION TONIGHT/SATURDAY. SOLID SURFACE
CYCLOGENESIS OVER SOUTHERN UTAH WOULD INDICATE THAT THE SOUTHWEST
QUADRANT OF UTAH SHOULD SEE THE HEAVIEST PRECIP EARLY IN THE
EVENT.

LATER IN THE WEEKEND THE PICTURE BECOMES A BIT MORE MUDDLED OVER
UTAH AS THE VARIOUS GUIDANCE INDICATE THE FAIRLY STRONG
FRONTOGENESIS SHIFTS SOUTH IN THE ARIZONA THROUGH SOUTHWEST
COLORADO. LESS FORCING OVER UTAH WOULD SUGGEST THAT PRECIP...
THOUGH STILL WIDESPREAD...MAY NOT BE AS INTENSE HEADING INTO
SATURDAY NIGHT/SUNDAY. ONE AREA THAT WOULD BE WORTH WATCHING WOULD
BE WEST-CENTRAL THROUGH NORTHEAST UTAH. MODEST TIGHTENING OF THE
MID-LEVEL THERMAL GRADIENT WOULD SUGGEST THAT PRECIP COULD
ORGANIZE AGAIN THROUGH CENTRAL/NORTHEAST UTAH SATURDAY NIGHT/EARLY
SUNDAY.

THE NEXT STORM SYSTEM DROPPING SOUTH OUT OF BRITCOL WILL PUSH THE
REMNANT OF THIS WEEKENDS THROUGH THROUGH UTAH SUNDAY NIGHT/MONDAY.
LOOKING AT AN EXPANSION OF PRECIP AGAIN ALONG AND AHEAD OF THE
TROUGH AXIS ON MONDAY.

&&

.LONG TERM (AFTER 00Z TUESDAY)...THE BROAD PACIFIC NORTHWEST TROUGH
IS EXPECTED TO MOVE THROUGH UTAH AND SOUTHWEST WYOMING MONDAY NIGHT
THROUGH TUESDAY...BRINGING A GOOD COLD FRONT ALONG WITH IT.
PRECIPITATION SHOULD BE PRIMARILY CONCENTRATED ALONG THE BOUNDARY AS
IT MOVES ACROSS THE FORECAST AREA. EC/GFS SHOW 700 MB TEMPS AS LOW
AS -16C TO -18C BEHIND THE FRONT...SO PRECIP SHOULD BE ALL SNOW.
WITH GOOD FGEN ALONG THE BOUNDARY...SNOW COULD BE
SIGNIFICANT...PARTICULARLY OVER NORTHERN AND CENTRAL UTAH. LATEST
GFS SHOWS A FASTER BUT MORE SPLIT SOLUTION THAN THE EC...WHICH
INDICATES SOME SNOW LINGERING OVER SOUTHEAST UTAH THROUGH EARLY
WEDNESDAY.

MODELS INDICATE HIGH PRESSURE RETURNING BEHIND THE EXITING STORM
SYSTEM FOR THE MIDDLE TO LATTER PART OF THE UPCOMING WEEK. THIS WILL
RESULT IN DRY CONDITIONS...WITH TEMPERATURES PROGGED TO RETURN BACK
TO OR ABOVE SEASONAL NORMS BY DAY 7.

&&

.AVIATION...VFR CONDITIONS ARE EXPECTED AT THE SLC TERMINAL
THROUGHOUT THE DAY. SHOWERS IN THE VICINITY OF THE TERMINAL WILL
DROP CIGS TO OR BELOW 6000 FT AGL AT TIMES THIS AFTERNOON. THERE IS
A 30 PERCENT CHANCE OF MVFR CONDITIONS DEVELOPING IN RAIN AND SNOW
SHOWERS. THE TERMINAL SHOULD SEE SOUTHERLY WINDS DURING THE DAYTIME
HOURS.

&&

.SLC WATCHES/WARNINGS/ADVISORIES...
UT...WINTER STORM WATCH FROM THIS EVENING THROUGH SUNDAY EVENING FOR
     UTZ517-518.

WY...NONE.
&&

$$

SHORT TERM...CONGER
LONG TERM/AVIATION...TRAPHAGAN

FOR MORE INFORMATION FROM NOAA/S NATIONAL WEATHER SERVICE VISIT...
HTTP://WEATHER.GOV/SALTLAKECITY (ALL LOWER CASE)

FOR FREQUENTLY ASKED QUESTIONS ABOUT THE AREA FORECAST DISCUSSION
VISIT...
HTTP://WEATHER.GOV/SALTLAKECITY/GENERAL/AFD_FAQS.PHP (ALL LOWER CASE)



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